Design of Microstrip Diplexer with Wide Band-stop

Abstract

This paper introduces a three-port microstrip diplexer. The diplexer is made up of two band-pass filters based on symmetric microstrip electromagnetic band gap (EBG) structure and two 1/4 lambda micro-strips (lambda is the guiding wavelength at the resonant frequency of every filter.) The result of simulation shows that the micro-strip diplexer has excellent performances of lower insertion loss and higher suppression band-stop. Also, the second harmonic falls into the stopband and can be suppressed directly.